Coating composition of a styrene/allyl alcohol polymer and a polyisocyanate

Abstract

A coating composition in which the film-forming constituents are a styrene/allyl alcohol polymer and an organic polyisocyanate; the coating composition is particularly useful as a finish for appliances, such as refrigerators, stoves, washers, dryers and the like and is useful in coil coating sheets of steel and aluminum.

The invention claimed is: 
     
       1. A coating composition comprising 10-90% by weight of film-forming constituents consist essentially of 1. about 10-90% by weight, based on the weight of the film-forming constituents, of a styrene/allyl alcohol polymer of 90-70% by weight styrene and 10-30% by weight allyl alcohol having a hydroxyl content of about 3-9% by weight and a specific viscosity of about 0.4-0.8 measured at 25°C. using 10 grams of copolymer in 100 milliliters of methylethyl ketone; and   2. about 90-10% by weight, based on the weight of the film-forming constituents, of a blocked organic polyisocyanate adduct in which the blocked organic polyisocyanate adduct is the reaction product of a polyether resin or a polyester resin and an aliphatic or cycloaliphatic organic diisocyanate and having the isocyanate groups blocked with an alkyl ketoxime.   
     
     
       2. The coating composition of claim 1 containing up to 50% by weight, based on the weight of the film-forming constituents, of pigment. 
     
     
       3. The coating composition of claim 2 wherein the number ratio of hydroxyl groups of the styrene/allyl alcohol polymer to isocyanate groups of the organic polyisocyanate is about 0.5:1 to about 5:1. 
     
     
       4. The coating composition of claim 2 in which the blocked organic polyisocyanate is the reaction product of an alkylene oxide and polyol and an aliphatic diisocyanate or an alicyclic diisocyanate and having the isocyanate groups blocked with an alkyl ketoxime. 
     
     
       5. The coating composition of claim 4 in which the alkylene oxide is propylene oxide and the polyol is glycerine and the diisocyanate is methylene-bis(cyclohexyl isocyanate) and the blocking agent is methyl ethyl ketoxime. 
     
     
       6. The coating composition of claim 4 in which the alkylene oxide is propylene oxide and the polyol is trimethylol propane and the diisocyanate is methylene bis-(cyclohexyl isocyanate) and the blocking agent is methyl ethyl ketoxime. 
     
     
       7. The coating composition of claim 1 containing 0.01-0.10%, based on the weight of the film-forming constituents, of an organic metal dryer. 
     
     
       8. The coating composition of claim 1 wherein the film-forming constituents consist essentially of 1. about 30-70% by weight, based on the weight of the film-forming constituents, of the styrene/allyl alcohol polymer containing 90-70% by weight styrene and 10-30% by weight allyl alcohol and having a hydroxyl content of 5-8% by weight and a specific viscosity of 0.5-0.7; and   2. about 70-30% by weight, based on the weight of the film-forming constituents, of a blocked organic polyisocyanate which is the reaction product of a propylene oxide and trimethylol propone and methylene-bis-(cyclohexyl isocyanate) in which the residual isocyanates are blocked with methylethyl ketoxime.   
     
     
       9. The coating composition of claim 8 containing 0.01-0.1% by weight, based on the weight of the film-forming constituents, of a cobalt naphthenate dryer. 
     
     
       10. The coating composition of claim 8 containing 0.5-50% by weight, based on the weight of the film-forming constituents, of pigment. 
     
     
       11. An article coated with about 0.1-10 mil thick dried coalesced coating of the composition of Claim 1. 
     
     
       12. The coated article of claim 11 in which the article is a metal substrate of a ferrous metal or aluminum.